DE4212842C2 - Needle felt with cover layer and process for its production - Google Patents

Description

The invention relates to a needle felt made from mineral fibers according to a cover layer applied at least on one side the preamble of claim 1 and a method its manufacture according to claims 8 and 11.

Needle felting is usually done by needling mineral wool, if necessary using suitable needle aids - so-called additives - manufactured. Such needle felts have good mechanical stability as well as an outside good thermal insulation properties. Since such a na Delfelt usually without substantial organic content Resin-based binders are suitable like needle felts especially for thermal insulation in the high lower temperatures because of the practical the presence of organic chemical binder substances Decomposition products are unlikely to arise.

Despite the outstanding properties of needle felts in space general it can lead to difficulties if such Needle felts should be used for high temperature insulation len. The mineral fibers used generally have one Temperature resistance from approx. 500 to over 1000 ° C, whereby the most resistant mineral fibers usually also are the most expensive to manufacture. The typically out a defibrated glass or basalt melt on a large scale mineral fibers obtained on a scale, for example a temperature resistance of approx. 550 ° C.  

If a needle felt made of such mineral fibers goes to high temperature insulation is used, the company disintegrates sern, which causes heat to develop over a longer period of operation form bridges so that the thermal insulation is not permanent more is guaranteed.

It is therefore an object of the present invention to provide a Na to provide delfelt that is made of cheap, large technically producible mineral fibers can be formed and which can be used for high temperature insulation.

This task is solved with a view to a pro dukt by the features of claim 1, in procedural technical aspects due to the characteristics of Pa claims 8 and 11.

The fact that the needle felt on at least one side brought covering layer, the covering layer a temperature-resistant, hardened layer of essentially Lichen inorganic material, ensures that such a cover layer is the fibers of it the needle felt from high temperatures, especially those over 550 ° C, protects, so that a needle felt with such a can be used for high temperature insulation, without disintegrating the fibers of the needle felt fear.

A possible method for producing a needle felt from mineral fibers with a cover layer applied on one side is according to claim 8 that an aqueous slurry of mineral wool, an inorganic binder, namely silica sol, an opacifying agent and a transport agent is prepared;
the top layer is made from the slurry by suctioning off the slurry water; and
the cover layer is arranged on a needle felt.

Another possibility of a method for producing a needle felt with an at least one side applied top layer is that an aqueous slurry of mineral wool, an inorganic binder, namely silica sol, an opacifying agent and a transport agent is prepared;
the slurry is partially dewatered;
the slurried components are prevented from sedimenting by adding suitable agents; and that
the resulting mass is applied to the needle felt, whereby the cover layer is formed.

The fact that according to the invention the cover layer from the aq slurry of mineral wool, silica sol, a Opacifiers and a means of transport by suction of the sludge water is produced and this on a Na Delfilz is arranged, can be a product according to the invention be produced, which is able to mine ral fibers of the needle felt before disintegration at one Protect set at high temperatures.

A particular advantage of this method according to the invention is based on the fact that coated on both sides Needle felting can be made.

The production of a needle felt according to the invention Proverb 11 also has the advantage that complex molded parts made of needle felt with a top layer can be provided.

It is already known from EP-A-0 390 962, a Manufacture molded part on mineral wool, in which by stable and even accumulation of solid particles certain properties can be set on the molded part can. Teaches to produce such a molded part EP-A-0 390 962, slurrying mineral wool in water, this slurry with a silica sol and binder a cellulose derivative and with solid particles which to be attached to the fibers of the mineral wool offset. By suction of the sludge water is then a molded part made of mineral wool, which a almost homogeneous uniform distribution of the added solids particles, such as soot or the like. Such Moldings are used in particular for microwave absorption in the Radar range used.

However, EP-A-0 390 962 does not teach that to manufacture there Development of moldings disclosed methods for coating mineral wool products.

The measures of claim 2 have the advantage that the Formation of the top layer as a stiffening layer me mechanical properties, especially the bending stability of needle felt, improve.

Such needle felts with a stiffening layer can be produced in plate form, for example, so that they can be used for thermal insulation of larger areas.

Such needle felts are also ideal for insulating houses Holding devices, such as ovens, suitable because they especially due to their absence of binders during the Operating, for example an oven, not to smell education tend.  

The measures that the layer as the main components mineral fibers, especially aluminosilicate fibers, and silica sol as an inorganic Contains binders have the advantage that here due to the high temperature resistance of the Layer is guaranteed and secondly the main inventory Parts are all inorganic chemical in nature, so that they no significant zero even in the high temperature range subject to settlement processes.

Because the layer or top layer of the needle felt contains an opacifier a particularly high effectiveness of the top layer as thermi protection for the fibers of the needle felt. This is because is based on the fact that infrared radiation in particular Opacifiers such as metal oxides, especially titanium dioxide, difficult or impossible to penetrate and even at it be reflected.

Because the needle felt is irrelevant in terms of fire technology Contains amount of a polysaccharide according to claim 4, can the advantages of this polysaccharide or polysaccharide derivatives, such as methyl cellulose, for the accumulation of solids particles, such as metal oxides, especially titanium dioxide the fibers of the mineral wool during the manufacture of the Na delfilzes can be used without the fire protection class is affected in any way.

The needle felt according to claim 5 also with opacifier to move has the advantage that this still a higher temperature resistance of the entire needle felt with Covering layer results because the opacifier, for example a metal oxide, preferably titanium dioxide, the through radiation of the needle felt with infrared radiation largely prevented.

A particular advantage of this measure is that establishes that technically predetermined layer thicknesses of both Cover layer as well as the needle felt with cover layer for  a certain high temperature use can be observed can by simply adding opacifiers to the needle felt itself is introduced. This is particularly advantageous in which is the opacifier before needling the fibers of the Avi is vaguely admitted.

Another way to add the needle felt Equipping opacifiers is that the needle felt before applying the top layer with an opacifier Water suspension, in particular a TiO₂ water suspension, is flooded and this suspension from the needle felt is filtered, the fine particles of titanium dioxide spread out in the needle felt.

Are the insulation properties typically 2-3 mm thick layer is not enough to the underlying needle To protect felts, opacifiers can be in the needle felt be introduced without the layer thickness or the total Thickness of the needle felt with top layer with even improved Increase temperature resistance.

The measures of claim 6 have the advantage that with the specified bulk densities of the needle felts for every need Needle felt of a suitable bulk density can be selected.

The measures of claim 7 have the advantage that the company the needle felt from the technically usual mineral fibers can be selected.

The needle felt according to claim 9 as a filter in a filter device, then the aqueous slurry Mineral wool, silica sol, an opacifier and a Means of transport through the needle felt, for example Pour on the needle felt and then apply the slurry Sucking off water has the advantage that a ratio nelles two-step procedure is available. A  Such a two-step process is quick and allows it therefore, large quantities of needle felts with a top layer in the to manufacture on an industrial scale. This happens in the Usually practically by the fact that the company water components, in particular aluminosilicate fiber components, into the water poured into the sludge tub the. The other components of the Slurry added, namely silica sol as an inorganic Binder and a polysaccharide, especially a poly saccharide derivative, which is chemically a methyl cellulose and for example under the trade name Phrikolat is available, as well as the opacifier to be added, at for example titanium dioxide.

Preferably, the opacifying agent is simultaneously with the Means of transport, especially methyl cellulose added. This has the consequence that the solid particles, for example instruct titanium dioxide, together with the silica sol binder the fibers migrate and are deposited there. Under the Microscope it can be determined that the deposit is island-like, especially in the form of dots on the mineral fibers follows.

The slurry is placed on the needle felt preferably simply by pouring the needle felt over it Slurry, which is then, for example, on a suction tape is drained, with the needle felt during suction acts as a filter.

This suction process causes the slurried Components on the surface facing the slurry of the needle felt and by suction it ver be pressed. After drying, one forms hardened top layer with the desired warmth insulation properties.  

The measures of claim 11 have the advantage that a Cover layer separately on a filter carrier, such as a gauze similar network of mineral fibers can be formed which then on any substrate, even on a Na delfelt, can be applied.

In particular, can be ge with this method grab packed cover layers because the filter is off flowing sludge water does not have such a large flow resistance stand offers like a needle felt.

However, if a needle felt is used as the substrate, then hereby also special productions, for example thicker ones or thinner layers and / or needle felts, which are outside of routine operation can be established.

The measures of claim 10 have the advantage that complicated - for example non-planar - surfaces of needle felt zen by spraying an appropriate slurry of Mineral wool, silica sol, an opacifier and a Means of transport can be provided with a cover layer nen.

Silica and / or a cellulose derivative according to claim 14 as a means to prevent sedimentation, has the advantage that it is cheap and in terms of quantity fire-safe substances available stand.

According to claim 15 to press and / or dry step close, has the advantage that this makes it strong on the one hand compacted cover layers can be made available and secondly through a special drying step, in a tunnel oven or the like, a quick one Curing of the top layer can be achieved.  

In particular, it is also possible in the still wet deck layer hot parts, especially electrical components, lightly push it in so that the layer is in place who comes into contact with the hot part immediately hardens and thereby fixes the part on or in the layer becomes.

Further advantages and features of the present invention he give themselves based on the description of execution examples len and based on the drawing.

It shows:

Fig. 1 shows a needle felt according to the invention with a cover layer.

To produce a needle felt 1 , glass wool, which is produced, for example, by the TEL process, is needled to a bulk density of approximately 80 kg / cm 3 using a suitable finishing agent, for example based on mineral oil. The finish is an opacifier, in the example TiO₂ added, so that even when needling the fibers of the mineral wool used there is a distribution of the opacifying agent within the needle felt, whereby heat radiation does not or only to a small extent inside the needle felt can penetrate.

To apply a top layer 2 , which comprises a temperature-resistant, hardened layer of essentially inorganic material, the slurry tub contains a mixture of aluminosilicate fiber as a mineral fiber, silica sol as a binder, TiO₂ as a clouding agent and phrikolate in an approximately 5000 l Add methyl cellulose as a polysaccha derivative in the following quantitative ratios:

43.3% by weight of aluminosilicate fiber
43.3% by weight of silica sol (40%)
13.0% by weight of TiO₂
0.4% by weight phricolate

To produce the top layer 2 , the aluminosilicate fibers are first added to the water filled into the container. With constant stirring, the other components of the slurry are added, namely silica sol and phricolate as well as the solid particles of TiO₂ to be added. It is particularly advantageous to add the phricolate as a polysaccharide derivative at the same time as the TiO₂ as solid particles to be added. This has the consequence that the TiO₂ migrate together with the silica sol binder to the alumosilicate fibers and are deposited there. It can be seen under the microscope that the deposit is island-like, in particular in the form of dots, on the mineral fibers.

The polysaccharide derivative thus serves - in the example case that Phrikolat - as a means of transport, which TiO₂ as turbidity medium and silica sol as a binder to the fibers trans ported.

Although this island-like accumulation of the opacifier, in Example trap TiO₂ to the fibers, for example Alumo silicate fibers, basically also with that in industry water is available, it is advisable to the conductivity of the sludge water by adding the Conductivity-increasing agents, in the example Magne sodium sulfate, to a value in the range of 900 to 1000 µS / cm adjust to the addition of the TiO₂ more effectively to ge design.  

As soon as the conductivity of the sludge water on the suitable value of conductivity is reached, it comes after Add silica sol and polysaccharide derivative, for example wise phricolate, for attachment to the aluminosilicate fibers, without working with an excess of these components must become. At the same time this ensures that Opacifiers, especially TiO₂, together with the binding medium to the mineral fibers, in the example aluminosilicate fiber, wander, so that only so much opacity must be added to the slurry as for the Attachment to the mineral fibers is desired. After the arrival store on the mineral fibers - here on the aluminosilicate fibers - The remaining water is completely pure and must be removed after Ent the mineral wool at most a filtering process be trained to mineral still present in the water recover fiber particles.

To arrange the top layer 2 on the needle felt 1 , the aqueous slurry of mineral wool, silica sol as a binding agent, TiO₂ as an opacifier and Phrikolat as a trans port agent and polysaccharide derivative poured onto a needle felt 1 as a filter and dewatered on a suction belt as a filter device. The slurried components sediment on the surface of the needle felt 1 and form the cover layer 2 after a drying process. Here, a product 3 according to the invention, namely a needle felt 1 with a cover layer 2 , can be produced. Products 3 of this type can be used in particular for high-temperature insulation, for example oven ovens or baking ovens.

A further possibility of producing a product 3 according to the invention is not to filter the aqueous slurry from mineral wool, silica sol as a binder, TiO₂ as an opacifying agent and phrikolate as a means of transport and polysaccharide derivative via a needle felt 1 , but via a gauze-like structure made of mineral fibers, where only an insulated layer with the desired properties arises, which can then be applied to a needle felt 1 or another mineral wool product while still wet and then after a pressing or drying and curing process with a mineral wool part, in the example, a needle felt.

Another way of producing a product 3 according to the invention is to partially dewater a partially dewatered slurry of mineral wool, in the example aluminosilicate wool, silica sol as a binder, TiO₂ as an opacifying agent and phrikolate as a means of transport, then the slurried constituents by adding silica to prevent and Tylose as a cellulose derivative on sedimentation and this mixture is then aufzu a needle felt 1 splash, also resulting in a covering layer 2 results, which connects after pressing and curing firmly with the underlying needle felt. 1 In the example, a mixture of 54 wt .-% silica sol, 25 wt .-% Alumosilikatfa ser and 21 wt .-% TiO₂ is used for spraying.

With this variant of the method, a needle can easily be used felt with opposite cover layers be put.

This method also creates a product 3 according to the Invention, which has excellent thermal insulation properties, the cover layer 2, which is generally 2-3 mm thick, due to the opacifying agent TiO 2 and the aluminosilicate fibers, the fibers 4 of the needle felt 1 before temperatures above 550 ° C protects. Accordingly, such a product 3 is particularly suitable for use as a high-temperature insulation material.

Claims (16)

1. needle felt made from mineral fibers,
characterized in that
it is provided with an at least one-sided cover layer ( 2 );
the cover layer ( 2 ) comprises a temperature-resistant, fully hardened layer of essentially inorganic material; and that
the layer contains mineral fibers, in particular aluminosilicate fibers, as well as silica sol as an inorganic binder. 2. Needle felt according to claim 1, characterized in that that the layer is a stiffening layer. 3. Needle felt according to one of the preceding claims, characterized in that the layer is a haze medium, especially a metal oxide, preferably Contains titanium dioxide. 4. needle felt according to one of the preceding claims, characterized in that the layer is a fire technically irrelevant amount of a polysaccharide and / or a derivative thereof, in particular a Cellulose derivative, preferably methyl cellulose, ent holds. 5. Needle felt according to one of the preceding claims, characterized in that the needle felt ( 1 ) also contains an opacifier, in particular metal oxide, preferably titanium dioxide. 6. Needle felt according to one of the preceding claims, characterized in that the needle felt ( 1 ) has a bulk density of approximately 50 to 140 kg / m³, in particular 60 to 90 kg / m³, preferably 80 kg / m³. 7. Needle felt according to one of the preceding claims, characterized in that the fibers ( 4 ) of the needle felt ( 1 ) are selected from the group consisting of: basalt fibers, aluminosilicate fibers, ceramic fibers and glass fibers. 8. A process for the production of a needle felt ( 1 ) from mineral fibers with an at least one-sided top layer ( 2 ) which contains mineral fibers and silica sol as an inorganic binder as main components, an aqueous slurry of mineral wool, silica sol, an opacifying agent and a transport agent being prepared becomes;
wherein the cover layer ( 2 ) is produced from the slurry by suctioning off the slurry water; and where
the cover layer ( 2 ) is arranged on a needle felt ( 1 ). 9. The method according to claim 8, characterized in that
the outer layer (2) is arranged, characterized in the needle felt (1) in that the needle felt (1) in a tervorrichtung Fil is presented as a filter;
the slurry is applied to the needle felt ( 1 ); and
the slurry water is suctioned off over the needle felt ( 1 ), the slurried components sedimenting on the surface of the needle felt ( 1 ) and thus form the cover layer ( 2 ) after drying. 10. The method according to claim 8, characterized in that a filter is presented in a filter device;
the slurry is applied to the filter; and
the sludge water is suctioned off through the filter, the slurried components sedimenting on the upper surface of the filter and the still wet cover layer ( 2 ) thus formed is arranged on the needle felt ( 1 ), the filter is removed if necessary and the cover layer ( 2 ) is dried is cured. 11. A process for the production of a needle felt ( 1 ) from mineral fibers with an at least one-sided applied top layer ( 2 ), which contains mineral fibers and silica sol as an inorganic binder as main constituents, an aqueous slurry of mineral wool, silica sol, a Trübungsmit tel and a means of transport is prepared; in which
the slurry is partially dewatered;
the slurried constituents are prevented from sedimenting by adding suitable agents; and where
the resulting mass is applied to the needle felt ( 1 ), whereby the cover layer ( 2 ) is formed. 12. The method according to claim 11, characterized in that spraying is used to act on the needle felt ( 1 ). 13. The method according to claim 12, characterized in that that a mixture of 45-55% by weight for spraying Silica sol, 20-40% by weight mineral wool and 10-25 % By weight of titanium dioxide is used. 14. The method according to any one of claims 11 to 13, characterized characterized in that silica and / or a cellulose sederivat be used as a means. 15. The method according to any one of claims 9 to 14, characterized characterized in that a pressing and / or drying step is connected. 16. The method according to any one of claims 9 to 15, characterized characterized in that the sludge water on a Leit ability of at least 700 µS / cm, expediently at least 800 µS / cm and preferably to a value in Range from 900 to 1000 µS / cm is set.